The present invention generally relates to the field of production of beverages or other liquid comestibles on the basis of ingredients contained in a capsule.
Such capsules are known for being inserted in matching beverage production machines (e.g. coffee machines). After being placed in an extraction chamber of the beverage production machine, water is injected into the capsule. The water will interact with the ingredients contained in the capsule. As a result of the interaction, a beverage or other comestible will be produced which can then be obtained from the capsule.
The invention preferably uses capsules which are hermetically sealed at a production site and which are inserted into the extraction chamber of the beverage production machine while still being in the sealed state. The capsule is opened both at the water inlet face for injection injecting pressurized water into the capsule as well as at the beverage outlet face for delivering the beverage. Openings on both sides may be produced by dedicated members of the machine. Note that these members can be driven manually, e.g. via a lever mechanism, or automatically by a motor.
EP 870 457 A1 and WO 94/02059 show extraction methods and extraction machines for essentially symmetrical capsules.
WO 94/01344 also describes a symmetrical capsule.
When water is injected into the interior of the capsule, especially when using ground coffee powder as an ingredient, it has to be assured that the water will be homogenously distributed all over the ingredients. A heterogeneous flow distribution of the water through the ingredients will lead to a poor quality or an unreliable quality of the produced beverage.
One known solution consists in having the water enter the interior of the capsule at a plurality of openings such that water distributes evenly across the whole transversal section of the capsule. However, this leads to a rather complex machine which has to be provided with a plurality of perforation/water injection members to this regard. Furthermore, the production of a plurality of openings requires a high closure force to be able to correctly pierce through the capsule for the injection of water. The required force is even higher for capsules containing ground ingredients in a compacted form.
Another issue, especially when extracting coffee from ground coffee powder containing capsule, is to control the flow rate of the usually pressurized hot water through the interior of the capsule. Depending on the kind of coffee to be produced, different flow rates and pressures inside the capsule have to be guaranteed. In particular, flow rates are usually relatively slow for capsules containing ground coffee in compacted form. Too slow of a flow rate may also negatively impact the extraction of coffee compounds.
Another issue is that when a “long” beverage (e.g., 110 mL or more) is desired, the solution usually consists in passing a higher amount of water through the ingredients. However, this may result in over-extracting the ingredients and to bitterness issues of the final drink.